Hale RSD - Manual (Page 58)

❑ Preventive Maintenance
58 RSD Series Single-Stage PTO Pumps
p/n: 029-0020-92-0
Worn Clearance Rings and Impeller Hubs
Before assuming that clearance ring wear is at fault or that clearance ring
replacement requires pump disassembly, it is advisable to thoroughly check
other possible causes of low performance.
Clearance rings limit the internal bypass of water from the discharge side of the
pump back to suction. The radial clearance between the impeller hub and the
clearance rings is only a few thousandths of an inch when new. In clear water,
the clearance rings continue to effectively seal for many years of operation.
In dirty or sandy water, the impeller hub and clearance rings wear faster. The
more wear, the greater the bypass and lower pump performance.
It should not be necessary to replace clearance rings until a loss in pump per-
formance is noticed during the annual test – see “Performance Testing” on
page 57. For clearance ring and impeller service, see heading “Impeller” on
page 83.
Often, replacing the clearance rings reduces the bypass and restores the pump
to near original performance. A complete restoration requires that the impeller
also be replaced. See Section 6.6 “Removing the Gearbox Only” on page 76
for maintenance and repair information if pump disassembly is required.
Anode Check
Hale offers two types of anodes
(consumables):
❑ Zinc anode - recommended for
all pumps where corrosion is an
issue, including brackish or salt
water exposure. Zinc anodes
should be inspected every
twelve (12) months.
❑ Magnesium anode - available if
the pump already uses zinc
anodes and galvanic corrosion
is still a concern. Magnesium anodes, which are consumed at a faster rate,
should be inspected ever three (3) or four (4) months. Magnesium anodes
contain a notch in the hex head for identification.
Replace anodes when over 75% of the metal has been consumed. Perfor-
mance of the anode life varies with water quality and pH. Anodes conform to
MIL Spec. A180001.
Figure 4-4: Hale Anode